Which equation matches the sentence?
column a column b
1.
three less than 9 times a number is 21.
2.
the sum of 3 times a number and 9 is 21.
3.
the difference of 9 times a number and 3 is 21.
4.
nine less than 3 times a number is 21.
a.
3n + 9 = 21
b.
9n – 3 = 21
c.
3n – 9 = 21

Atype of plant is introduced into an ecosystem and quickly begins to take over. a scientist counts the number of plants after mmonths and develops the equation p(m)= 19.3(1.089)^m to model the situation. most recently, the scientist counted 138 plants.assuming there are no limiting factors to the growth of the plants, about how many months have passed since the plants werefirst introduced? a)o 6.1b)0.6.6c)10 72d)o 23.1